&QUOT;We can only hear them over our radios, but I've got a feeling they're with us all the time.&QUOT;Mars - 2068 AD: a mission to the red planet ends in disaster as the crew make an unprovoked attack on the complex of the Mysterons. Sentient computers left behind by the dying Mysteron race announce that they will destroy all life on Earth in a slow but effective war of nerves. Their first act of retaliation will be the assassination of the World President...

&QUOT;There's some sort of trouble with Delta Tango one niner. They won't open the doors.&QUOT;The Mysterons threaten the life of the Director General of the United Asian Republic and Spectrum swings into action to protect him as he prepares to board his private plane at London Airport. But the Mysterons have sabotaged a DT19 passenger jet and used retrometabolism to recreate it - under their control!

&QUOT;Now let's assume Macey counted correctly and heard Big Ben strike thirteen. What's the only explanation?&QUOT;The Mysterons threaten to destroy London and a truck carrying an atomic device goes missing in the city. The only clue to its whereabouts is the truck driver, found unconscious in the street. He claims that before he was struck down he distinctly heard Big Ben strike thirteen...

&QUOT;D'you mean to tell me that it was Major Brooks himself who exploded?&QUOT;When the Mysterons threaten the life of the Supreme Commander of Earth Forces, Scarlet and Blue are assigned to escort him to SHEF HQ in New York to chair a briefing on the Unitron, an advanced unmanned tank. But the Commander's aides, Major Brooks and Colonel Storm, are killed in a car crash and both become Mysteron agents...

&QUOT;The tables are turned. The manhunt for Captain Black is on!&QUOT;The Mysterons make their first mistake when Captain Black, revealed to have become a Mysteron agent, breaks into the Culver Atomic Centre and is exposed to radioactivity that will enable Spectrum to track him with directional geiger counters. But as the net closes, Black kidnaps Symphony Angel and holds her hostage...

Written by Richard Conway and Stephen J. MattickDirected by Ken Turner

&QUOT;That Magnus should keep his hands out of the way.&QUOT;The Mysterons' cryptic threat to &QUOT;kill time&QUOT; has the Spectrum personnel stumped until Magenta realises that their target is General Tiempo, the Commander of Western Region World Defence. Tiempo is due to have an operation which involves a new Cerebral Pulsator, but his neurosurgeon Dr. Magnus has already become a Mysteron agent!

&QUOT;Remember, time is against us. Every second takes that rocket nearer its target.&QUOT;The Mysterons engineer the launch of a Variable Geometry Rocket from Base Concord and their agent, Major Reeves, escapes with the destruct mechanism and target information. While the Angels are despatched to track down Reeves, Scarlet and Blue are sent to Base Concord where they learn that the rocket's target is the base itself!

&QUOT;Sir, I don't think you appreciate that the man is dead.&QUOT;&QUOT;That's no excuse!&QUOT;The Mysterons threaten to kill Colonel White and after their initial attempt fails, White elects to leave Cloudbase so as not to place the other Spectrum agents in jeopardy. He goes into hiding on the USS Panther II submarine, unaware that his steward is a Mysteron agent...

&QUOT;Look - Angels! The girls have come to escort us!&QUOT;When the Mysterons threaten to kill one of the Angels, Scarlet and Blue are sent to Paris to escort Destiny back to Cloudbase. But Captain Black engineers the destruction of three newly-built Angel aircraft - Mysteronised, the Interceptors are set to target Destiny!

&QUOT;You will never solve the mystery of the Mysterons.&QUOT;At a secret conference in a hidden Spectrum base housed beneath the hunting lodge of a private African game reserve, Dr. Giadello announces the development of two devices that will turn the tide for Spectrum in their struggle with the Mysterons. But the Mysterons intend to sabotage the conference from within...

&QUOT;Believe me, before this day is out you'll need all the help you can get.&QUOT;When the Mysterons threaten to destroy key links in the Frost Line Outer Space Defence System, Scarlet and Green investigate the mysterious deaths of the personnel at Red Deer Base. The pair are baffled: radiation and toxicity levels read negative and there appears to be no reason for the deaths of the men...